Patch to gPXE dhcp command

I just released a patch to gPXE that modifies the dhcp command so that it can iterate over multiple interfaces. The stock dhcp command only accepts a single interface as an argument, which can be a problem if you are trying to boot on a machine with multiple interfaces. The builtin autoboot commands attempts to resolve this, but is only useful if you expect to receive appropriate boot parameters from your dhcp server.

My patch extends the dhcp command in the following ways:

It allows the “dhcp” command to accept a list of interfaces and to try them in order until it succeeds, e.g.:

gPXE> dhcp net0 net1 net2

In order to preserve the original syntax of the command, this will fail on an unknown interface name: